Vacuum mold with kerf insertion system

ABSTRACT

A MOLD FOR THE FORMING OF A CEILING TILE BY THE VACUUM MOLDING TECHNIQUE WHEREIN THE END PRODUCT IS PROVIDED WITH A BUILT-IN KERF. A FRAME IS PREPARED HAVING THE DESIRED SIZE AND SHAPE. THE KERF DEFINING STRUCTURE WHICH IS TO BE EMBEDDED IN THE FINISHED PRODUCT TO FORM THE KERF IS PLACED AROUND THE EDGE OF THE FRAME. THE FRAME IS THEN IMMERSED IN A TANK CONTAINING A LIQUID PULP SLURRY. A VACUUM PULLS ON ONE SDE OF A SCREEN RESULTING IN A BUILDUP OF WET PULP FIBERS ON THE REVERSE SIDE OF THE SCREEN. A PREIPHERAL VACUUM MEANS ASSISTS IN THE FORMATION OF THE PERIPHERAL EDGES OF THE CEILING TILE. THE KERF DEFINING STRUCTURE IS RELEASABLE HELD AGAINST THE PREIPHERAL EDGE VACUUM MEANS BY A REMOVABLE PERFORATED Z-SHAPED   SUPPORT ELEMENT. THE PULP FIBERS BUILD UP AROUND THE KERF DEFINING STRUCTURE AND ACTUALY RESULT IN THE KERF DEFINING STRUCTURE BEING EMBEDDED IN THE FINISHED PRODUCT.

Feb. 2,1971 w, LUEDERs ETAL 3,560,335

VACUUM MOLD WITH KERF INSERTION SYSTEM Filed Aug. 29. 1967 INVENTOR5 ROBERT w. LUEDERS WASHINGTON H. PHILLIPS ATTORNEY United States Patent 015cc 3,560,335 Patented Feb. 2, 1971 U.S. Cl. 162-387 1 Claim ABSTRACT OF THE DISCLOSURE A mold for the forming of a ceiling tile by the vacuum molding technique wherein the end product is provided with a built-in kerf. A frame is prepared having the desired size and shape. The kerf defining structure which is to be embedded in the finished product to form the kerf is placed around the edge of the frame. The frame is then immersed in a tank containing a liquid pulp slurry. A vacuum pulls on one side of a screen resulting in a buildup of wet pulp fibers on the reverse side of the screen. A peripheral vacuum means assists in the formation of the peripheral edges of the ceiling ti e. The kerf defining structure is releasably held against the peripheral edge vacuum means by a removable perforated Z-shaped support element. The pulp fibers build up around the kerf defining structure and actually result in the kerf defining structure being embedded in the finished product.

CROSS-REFERENCE TO RELATED APPLICATION The invention herein is directed to an improved mold structure for use in carrying out the process set forth in copending application Ser. No. 664,074, filed Aug. 29, 1967.

BACKGROUND OF THE INVENTION Field of the invention The invention is directed to a mold for vacuum forming of ceiling tile with a built-in kerf.

Description of the prior art When attempting to provide a ceiling system with a hidden suspension system, a kerf or groove is cut in the sides of the individual tiles. A T-shaped support system is used, and the T member is inserted into the kerf or groove in the sides of the tiles to support the tiles. Normally this kerf or groove is cut in the finished tile using conventional mechanical cutting tools.

The invention herein contemplates the forming of the individual tiles with a built-in kerf that is reinforced by a metal structure. Through the use of the invention set forth in this application, the mechanical cutting step is eliminated, and a simplicity of manufacture is secured. A metal kerf defining structure is used to define the kerf or groove that will exist in the finished tile product. By using this kerf defining structure with a vacuum forming technique, the metal kerf defining structure is actually embedded within the tile structure during the time the tile is being formulated by the vacuum forming technique. The finished product is thus provided with a kerf and edge strengthening structure, both being provided by the kerf defining structure embedded within the tile.

SUMMARY OF THE INVENTION The invention is directed for a mold used to form ceiling tiles with a built-in kerf. The mold has a frame structure which establishes the general size of the tile. A screen on the frame extending across the face of the tile and along the edges of the tile cavity forms the surface on which the tile is built up by the vacuum forming technique. A metal kerf defining structure is supported along the edge screens in the region where the edge of the tile will be formulated. By the placing of a vacuum on the reverse side of the screen, the fiber particles are attracted to the screens surface and form the ceiling tile. Specifically, the fibers form around the kerf defining structure and result in the kerf defining structure being embedded in the finished product. Drying of the fiber material then provides a ceiling tile structure with a kerf or groove provided by the kerf defining structure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the vacuum mold using the inventive process; and

FIG. 2 is a sectional view of the mold in the region of the kerf formation structure.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the preferred embodiment set forth in the figures there is shown the perforated support plate 2 which separates the suction box 4 from the mold chamber and assembly 6. The suction box is connected to a filtrate drain and vacuum connection 8. The support p ate 2 carries the mold assembly 6 and has a plurality of perforations 10 to permit the forming of a vacuum inside the mold cavity and to permit the passage of water to the filtrate drain.

The mold assembly consists of a pattern support 12 supporting a support screen 14. The patt rn support 12 is nothing more than a series of vertical dividers arranged in the egg-crate divider pattern with their outer contour being shaped closely to that contour which it is desired to impart to the ceiling tile. The support screen 14 is supported by the pattern support 12 and the screen is shaped to the exact contour that it is desired to impart to the ceiling tile. It is against this screen that the fibers are deposited to form the ceiling tile.

A support bar 16 is used to hold the peripheral edge of the screen in position and carries the vacuum sideboard 18. The sideboard 18 is connected by lines 20 to the filtrate drain and vacuum connection so that the sideboard screens 22 will have a vacuum on their inner sides. It is the vacuum sideboards that determine the peripheral shape of the tile unit and assist in the forming of the kerf system.

Referring to FIG. 2, a Z support element is used to support a metal kerf defining structure 26. The upper section 28 of the Z support rests upon the top surface of the vacuum sideboard 18 and supports the Z support in position. The lower portion of the Z support is used to support the metal kerf in its proper position. The connecting element 32 of the Z support rests against the screen 22. The Z support is also useful to assist in the removal of the finished tile unit from the frame or mold since the upper section 28 of the support may be readily grasped and used to raise the completed tile assembly from the frame of the vacuum mold assembly. The chosen thickness of the intermediate portion 32 automatically determines the amount of cut-back above the kerf which is necessary to accommodate the vertical web of a typical suspension member. Further, the intermediate portion 32 and the lower portion 30 of the Z support are perforated to allow passage of water from the slurry solution through the sections into the vacuum area of the sideboard structure.

The metal kerf defining structure is composed of a straight section 34, an intermediate curve section 36, and an angular section 38. The straight section 34 rests against the screen structure when the metal kerf is placed in the mold assembly. The curve section 36 rests upon the lower section 30 of the Z support, and it is this relationship which holds the metal kerf in position in the mold assembly. After the tile assembly 40 has been formed by the vacuum slurry technique, the angular section 38 of the metal kerf will be embedded in the tile structure. The curved intermediate section 36 will also be embedded in the tile structure and its outwardly facing curved area 42 will form the kerf for the tile unit. The metal kerf defining structure 26 has all of its sections provided with a plurality of perforations which are of such a size as to permit the passage of the water from the slurry solution into the vacuum sideboard, but small enough to prevent the passage of the fibers through the perforations.

The placing of the vacuum sideboard along the edge of the ceiling tile with the metal kerf being placed adjacent to the vacuum sideboard, gives a uniform buildup of fibers around the metal kerf and along the side structure of the tile unit. The proper buildup of the fibers is best secured by drawing the fibers with a vacuum action which acts normal to the plane of the forming surface. Consequently, the fibers are uniformly deposited on the contour screen 14 due to the positioning of the vacuum area below this screen so that the vacuum may act normal to this screen 14. Likewise, the vacuum sideboard permits the vacuum to act normal to the side area of the tile unit. Due to the positioning of the straight section 34 of the kerf structure 26 relative to the screen 22, the fibers will uniformly build up back of the straight section 34. The area 42, which forms the kerf, being in close proximity to the vacuum sideboard, will have the liquid drawn into this area 42 and subsequently into the vacuum sideboard. This will then provide a uniform buildup of the fibers around the intermediate curved section 36 of the kerf structure. The vacuum acting normal to the connecting section 32 of the Z support will provide a uniform buildup of fibers in this area. An alternative usage is the use of a two-way valve to permit pulling of vacuum around the kerf edge first, and, when the valve is in its second position, it would pull on both the edges and bottom. This gives better definition in the kerf, and could be used to increase density at this point so as to increase the strength 4 of the kerf. Also the kerf defining structure need not be used to define a kerf, but only to serve as edge reinforcing.

It will be obvious to those skilled in the art that various changes may be made without departing from the spirit of the invention; and, therefore, the invention is not limited to what is shown in the drawings and described in the specification, but only as indicated in the appendant claim.

We claim:

1. A mold for forming pulp articles by deposition from liquid pulp slurries, said mold comprising a box means connected to a source of vacuum, said box means having a perforated wall, a support screen spaced from the perforated wall and supported therefrom on the side of the wall away from the vacuum and used as the surface upon which the fibers are deposited to form the pulp article, vacuum box means positioned around the peripheral edges of the perforated wall and assisting in the formation of the peripheral edge of the pulp article being formed on the support screen, a perforated kerf defining structure easily removably positioned against said peripheral edge forming vacuum box means so that the pulp article will be formed around the kerf defining structure which provides the pulp article with a built-in peripheral kerf with the kerf defining structure made a part of the finished article, and an easily removable perforated support means for releasably holding the kerf defining structure against the peripheral edge forming vacuum box means so that the formed pulp articles and kerf defining structure may be easily removed from the mold.

References Cited UNITED STATES PATENTS 2,238,355 4/ 1941 Whitenack 52601 1,861,849 6/1932 Frobisher 162218X 3,137,614 6/1964 Harshberger 162231 S. LEON BASHORE, Primary Examiner A. A. DANDREA, JR., Assistant Examiner U.S. Cl. X.R. 162-228, 411 

